Amazing Dog Behavior - Cancer and Disease Detection in Humans

Golden retrievers have a great sense of smell, which is very useful in a bio-detection dog.
Golden retrievers have a great sense of smell, which is very useful in a bio-detection dog. | Source

Dogs - Friends and Helpers

Dogs can be wonderful companions and family members. They don’t perceive the world in exactly the same way as us, however. For example, they can’t see as many colors as us, but their senses of smell and hearing are much better than ours. Since dogs are clever animals that are usually eager to cooperate with us, their enhanced senses can be very useful to humans.

One exciting discovery about dog behavior is that dogs can detect certain diseases and medical problems in humans. Sometimes they need to be trained to accomplish these tasks, but in other instances dogs can identify a problem on their own without any training. Dogs can detect several types of cancer, low blood sugar in diabetics, the fact that an epileptic seizure is about to occur and - according to the results of research with one dog - an infection by Clostridium difficile.

Dogs are believed to detect diseases with their amazing sense of smell. This sense is at least 10,000 times stronger than ours and may be up to 100,000 times stronger. A dog's nose and brain have special adaptations for sensing and analyzing odors, which we lack.

Training Dogs to Detect Cancer

How Do Dogs Detect Cancer?

Cells produce and release volatile organic compounds, or VOCs. Cancer cells produce a different set of VOCs from healthy cells. Some of the VOCs are different from those made by normal cells, while others are the same but are present in a different proportion.

Volatile organic compounds escape from cells and leave the body in exhaled air, saliva, sweat, blood, urine or feces. Dogs can smell and recognize the distinct VOC or combination of VOCs made by cancer cells and can distinguish them from the VOCs made by normal cells.

Dogs detect the presence of the abnormal VOCs in sample containers very quickly. They are trained to show that they've found the chemicals by performing specific behaviors, such as tapping the sample container with their paw or nose or sitting in front of it.

According to the American Kennel Club, the ten dogs with the best sense of smell (in alphabetical order) are the basset hound, beagle, Belgian malinois, black and tan coonhound, bloodhound, bluetick coonhound, dachshund, German shepherd, golden retriever and Labrador retriever.

Bio-Detection Dogs

Cancer Types Detected By Dogs

Lung Cancer

Detecting early-stage lung cancer is difficult. There are generally no obvious symptoms and the normal detection methods aren't very reliable. It's very important to identify any cancer in its earliest stages to give the best chance for recovery.

Researchers in a 2011 experiment tested the ability of trained dogs to detect cancer VOCs in exhaled air. The dogs detected 71 cancer samples out of a total of 100. The dogs also detected that 372 samples out of a possible 400 did not contain cancer VOCs.

Interestingly, the dogs were not confused by the presence of cigarette smoke particles in the samples or by chemicals released by people suffering from COPD (chronic obstructive pulmonary disease). There does seem to be a specific chemical (or chemicals) released by lung cancer cells.

Lung and Breast Cancer

The Pine Street Foundation is a non-profit organization designed to support cancer patients and research the disease. In 2006 scientists representing the foundation trained five dogs to detect chemicals in the exhaled breath of lung and breast cancer patients. In an experiment, the researchers found that the dogs detected 99% of the lung cancer samples and gave a false positive result to only 1% of the normal samples. The dogs correctly identified 88% of the breast cancer samples and had no false positives.

In one experiment, a Labrador retriever was able to detect compounds released by colon cancer cells.
In one experiment, a Labrador retriever was able to detect compounds released by colon cancer cells. | Source

Colon Cancer

In 2011 another researcher studied the ability of one specially trained Labrador retriever to detect colon cancer in breath or stool samples. The dog correctly identified the presence or absence of cancer chemicals in 33 out of 36 breath samples and in 37 out of 38 stool samples. The stool experiment results were as accurate as colonoscopy results. This is a standard test for the presence of colon cancer and involves the use of a camera to photograph the inside of the colon.

Prostate Cancer

Dogs may also be able to detect prostate cancer by smelling urine. In 2015, the results of an experiment with two bomb-sniffing German shepherds were published. The dogs were given urine from 332 men with prostate cancer and 540 people without the disease. One of the dogs was 100% accurate in detecting the presence or absence of cancer. The other was 98.6% accurate.

In one trial, two German shepherds were very successful at detecting prostate cancer.
In one trial, two German shepherds were very successful at detecting prostate cancer. | Source

Double Blind Experiments

It's very important that experiments with cancer-detecting dogs are "double blind" experiments. At the start of a double blind experiment, the dogs and the observers are both unaware of which test containers contain cancer compounds and which are cancer free. This is very important, since observers may give unconscious signals with their body if they see that a dog is approaching the correct container. Dogs can pick up these signals and may indicate that a container contains cancer compounds simply because they notice that the observer is reacting in some way, even if the reaction is very slight.

When assessing any experimental results, it's important to consider factors that may have affected the outcome, such as sample size and the use or lack of a double-blind procedure. It's also important to note whether another organization is able to replicate the experiment and its results.

Training Medical Detection Dogs

Experimental Results

The results of the experiments with cancer detection dogs range from good to excellent. Possible reasons for this variability could be factors such as the differing abilities of the individual dogs or dog breeds used in the experiments, differences in their prior training or willingness to participate in the experiment or differences in the experimental design. The type and stage of the cancer may also play a role. Dogs may be able to detect some types of cancer better than others, or they may be able to detect cancer at one stage of development better than at another stage. More experiments need to be done and they need to involve a larger number of dogs.

Research with dogs is very important, not only because dogs can indicate the presence of cancer very quickly but also because their behavior demonstrates that cancer cells release specific chemicals. The ultimate goal is not to have groups of dogs working in medical labs. Instead, researchers hope to identify the molecules that the dogs are detecting and then create instruments that can correctly identify the presence of these molecules.

Labrador retrievers enjoy carrying objects, which can be useful for people with medical problems.
Labrador retrievers enjoy carrying objects, which can be useful for people with medical problems. | Source

Diabetes and Hypoglycemia

What is Type 1 Diabetes?

Blood glucose (or blood sugar) is an important substance because it's used by cells as an energy source. Insulin, a hormone made by the pancreas, triggers glucose to leave the blood and enter cells. In a person with type 1 diabetes the pancreas doesn't make insulin, so the person must obtain the hormone through injections or an insulin pump in order for their cells to absorb the necessary glucose.

What is Hypoglycemia?

Blood sugar can fall to a dangerously low level if a diabetic person receives too much insulin relative to the amount of glucose in their blood. This condition is called hypoglycemia, or low blood sugar.

Hypoglycemia can also develop if the person exercises too much, which uses up blood glucose, or if the person doesn't eat enough food, since the digested food supplies glucose to the blood.

Nighttime is especially risky for a person with Type 1 diabetes, since the blood sugar level may fall during sleep. Diabetics need to monitor their blood glucose level frequently and make adjustments to their insulin and glucose intake if necessary.

A Diabetic Alert Dog in the Family

Common Symptoms of Hypoglycemia

Common symptoms of hypoglycemia include sweating, shaking, weakness, anxiety, dizziness, headache, a rapid heart beat and confusion. Severe hypoglycemia can lead to seizures, coma and death. An affected person may not realize that their blood sugar is low, however, because the warning signs may be too weak or because of the confusion that develops. This is why a diabetic alert dog as a companion may be a life-saver as well as a friend.

Anyone who experiences symptoms that might indicate the presence of hypoglycemia should visit a doctor for a diagnosis and treatment plan.

Dogs For Diabetics

Diabetic Alert Dogs

Diabetic Alert Dogs are thought to sense a change in body or breath odor when a person with Type 1 diabetes is entering a hypoglycemic state, although it isn't known what chemical or chemicals the dogs are perceiving. Some dogs can detect high blood sugar as well as low blood sugar.

Diabetic alert dogs are trained to warn their owner in some way when they detect the signs of low blood sugar. They may jump up on their owner, lick them extensively, nudge them or sit and stare at them, for example. They may also be trained to bring insulin kits or food to the person or to contact other people. Some parents say that the diabetic alert dog in the family will wake them up during the night if their child is experiencing a dangerous drop in blood sugar.

There hasn't been much scientific research into the ability of dogs to detect low or high blood sugar, but scientists say that this ability is definitely plausible. Many diabetics who own diabetic alert dogs say that their dog's alerts are accurate and agree with the data recorded by their blood glucose monitor. They also say that their dog has given them a wonderful feeling of freedom and peace of mind and is a very close friend.

How Dogs Can Help People With Epilepsy

Seizure Alert Dogs

Some dogs can predict that a person with epilepsy is going to have a seizure soon, even when the person doesn't realize this. The warning time ranges from under a minute to forty five minutes - or even longer - before the seizure starts. The advantage of the prediction is that the person can move to a safe area so that they aren't injured during the seizure.

Dogs are being taught to take care of people during and after a seizure. The ability to predict a seizure is a special behavior shown by certain dogs and can't be trained, although it may be encouraged.

Some scientists think that seizure alert dogs are actually detecting the very early stages of a seizure that has already started rather than "predicting" the seizure. The changes in the person's brain may be creating chemicals which the dogs can smell. The dogs may also be detecting subtle changes in the person's behavior. Whatever the true explanation, dogs can be very helpful for epileptics.

The dogs indicate their discovery to their owner in a number of different ways. Some dogs paw their owners or bark. Others circle their owners, lick them, nudge them, push them into a sitting position or stare at them.

A Seizure Alert Dog in the Family

A Beagle That Can Detect the Clostridium difficile Superbug

Clostridium difficile, or C. diff, is a very troublesome bacterium that produces infections in hospitals, care homes or communities. It causes inflammation in the intestine and diarrhea, which are sometimes severe.

In late 2012 an article was published in the British Medical Journal which described the efforts of a two-year-old beagle named Cliff. Cliff was trained to detect C. diff in stool and in the air around hospital patients. After Cliff had received two months of training he was given 50 stool samples contaminated with C. diff and 50 samples without C. diff. Cliff correctly identified all 50 samples with the bacteria and 47 of the ones without bacteria.

Cliff was then taken to two hospital wards to smell the air around patients. He identified 25 out of 30 cases of infection and 265 out of 270 cases without the infection - and he took only ten minutes to inspect one ward! This is a much faster way to detect Clostridium difficile than using a conventional medical test. The faster the diagnosis, the sooner the treatment can begin.

Cliff's ability to detect Clostrium difficile is very impressive, but he is only one animal. We need to discover whether other dogs share Cliff's abilities.

Beagles have an excellent sense of smell, which can be very helpful for humans.
Beagles have an excellent sense of smell, which can be very helpful for humans. | Source

Buying a Medical Detection Dog

Dogs that can detect medical conditions or emergencies are very useful and their companionship may be very comforting to the affected person. The dogs undergo extensive training and are sometimes expensive to buy, costing many thousands of dollars. It's important that anyone who wants to buy one of these dogs goes to a reputable organization that trains and treats their animals well.

Hopefully more researchers will explore the ability of dogs to detect health problems. If the research shows that dogs can detect disease, more funding may be provided to the training organizations. The price of the dogs may then decrease, enabling more people to buy them.

Dogs can be wonderful and very loving pets. It's great that some can help us with medical problems as well. As more research is done, we may well discover more about the amazing abilities of dogs.

© 2012 Linda Crampton

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Comments 32 comments

SmartAndFun profile image

SmartAndFun 3 years ago from Texas

This is such a fascinating subject and a great article. Dogs are wonderful as pets, even when they have no other purpose than to be cute and allow us to pet them. However, dogs really are man's best friend when they are able to help us out in this huge way. Dogs have incredible detective powers amd I'm so glad humans have caught on to this and are putting dogs to work saving lives.


AliciaC profile image

AliciaC 3 years ago from British Columbia, Canada Author

Thank you for the visit and the comment, SmartAndFun. I agree - dogs are great pets, even when they can't detect disease! It's wonderful that some of them can identify the presence of medical problems, though.


billybuc profile image

billybuc 3 years ago from Olympia, WA

I had heard of this before, but not in the detail that you presented it. Dogs are amazing creatures, aren't they? Great job Alicia, and thank you for the great information.


AliciaC profile image

AliciaC 3 years ago from British Columbia, Canada Author

Hi, Bill. Yes, dogs are certainly amazing creatures! I love having them in my life. Thank you for the comment.


bdegiulio profile image

bdegiulio 3 years ago from Massachusetts

Amazing. I have seen and heard about this and it's amazing. They really are man's best friend. Great job, very interesting.


AliciaC profile image

AliciaC 3 years ago from British Columbia, Canada Author

Thanks, Bill. I appreciate your comment. Yes, dogs can be wonderful friends to humans! Their sense of smell is amazing, and it's great that they can help us detect disease and health problems.


drbj profile image

drbj 3 years ago from south Florida

Amazing is the right word, Alicia, to describe these dogs' ability to detect specific diseases. As long as the experiments are double blind the results can be conclusive. Otherwise you would have something like the 'Clever Hans' effect (as described in my hub: 'The Amazing Horse Who Could Count').

Voted up for your research and fascinating explanations.


Fossillady profile image

Fossillady 3 years ago from Saugatuck Michigan

I've heard of dogs detecting cancer, but I never knew how. Very interesting and encouraging data. I was wondering how they would apply the research. You're sitting in the doctors office and he says, I'll be right back with the cancer detector dog...hee. But then they explained how they would develop technology to detect the chemical odor dogs detect. Dogs are truly man's best friend!


AliciaC profile image

AliciaC 3 years ago from British Columbia, Canada Author

Hi, drbj. Yes, I had the "Clever Hans" effect in my mind when I was writing the section about double blind experiments! Good experimental design is so important in order to draw valid conclusions from an experiment. Thank you for the comment and the vote!


AliciaC profile image

AliciaC 3 years ago from British Columbia, Canada Author

Hi, Kathi. Thanks for the visit. The research with medical detection dogs is very encouraging! I'm hoping that more experiments are done, with more dogs being trained and tested in each experiment. It would also be great to discover if some dog breeds are better at detecting disease than others.

I think the research is wonderful, as long as the dogs are treated well and seem happy, which they have done in all the videos that I've seen. At least some of the organizations that train the dogs point out that their dogs live in people's homes and aren't kept in a kennel at the research facility, which I think is important.


mary615 profile image

mary615 3 years ago from Florida

Dogs are such amazing creatures! I read somewhere there was a nursing home and a cat who lived there could sense when a patient was about to die. The cat would go into their room and just sit there with them.

Very interesting article. I voted this UP and shared.


AliciaC profile image

AliciaC 3 years ago from British Columbia, Canada Author

Hi, Mary. I've heard about this cat, too. His name is Oscar (if we're thinking about the same cat). If the reports of his behavior are accurate, it's amazing that Oscar can sense that people are near death, but it's also wonderful that he decides to lie close to them as they die. Thank you very much for the vote and the share!


debbiepinkston profile image

debbiepinkston 3 years ago from Pereira, Colombia and NW Arkansas

Alicia, this is amazing and exciting news to me! What a great help these dogs will be to thousands of people! I hope that many more dogs will be trained for this purpose. We already know of the great service of seeing eye dogs, and now we have found another great service that dogs can offer their owners!

Thank you for letting us in on this valuable information!


AliciaC profile image

AliciaC 3 years ago from British Columbia, Canada Author

Thank you for the comment, Debbie! Yes, this is exciting information. It's wonderful that dogs can be great companions and can help us detect certain diseases, too. Service and assistance dogs can improve people's lives dramatically, and medical detection dogs are starting to do the same.


MartieCoetser profile image

MartieCoetser 3 years ago from South Africa

How very interesting! I am totally speechless! But buying a trained dog for personal use would be a bit selfish. An entire community should benefit from his talent. I am sharing this with all my friends in South Africa. Thank you, Alicia, for another most interesting hub coming from your pen. You are a walking encyclopedia!


Bob Bamberg profile image

Bob Bamberg 3 years ago from Southeastern Massachusetts

Great hub, Alicia! I was aware of some of the information you provide, but not in such detail. Your hard work made for a most interesting article.

I remember a documentary 6 or 8 years ago about a dog in the UK that warned his owner of her impending seizures. After all was said and done, they think it came down to the fact that the woman's index finger would twitch slightly about 15 minutes before she seized.

That would go along with the reference in your hub to dogs detecting the very onset of the seizure and not predicting it.

Great work. Voted up, useful and interesting.


Eiddwen profile image

Eiddwen 3 years ago from Wales

Such a gem on man's best friend ; in more than one way!!Thank you for this wonderful share.

Eddy.


AliciaC profile image

AliciaC 3 years ago from British Columbia, Canada Author

Thank you very much for the comment, Martie, and for sharing the hub with your friends! I appreciate your visit.


AliciaC profile image

AliciaC 3 years ago from British Columbia, Canada Author

Thank you very much for the comment and the votes, Bob, and thanks for sharing the interesting information, too! Dogs can be very perceptive, especially with the important people in their lives. It's amazing to think that the dog in your story may have been noticing something as slight as a finger twitch. His behavior must have been very useful to his owner!


kashmir56 profile image

kashmir56 3 years ago from Massachusetts

Hi my friend enjoyed reading this hub and you did a great job researching this has well. Dogs have a very great sense of smell and it will rival our own sense of smell very easy, dogs also never forget a smell as well. They are very amazing and fascinating creatures. Thanks for sharing this very interesting information it was a awesome read.

Vote up and more !!!

Wishing you a very Merry Christmas !


AliciaC profile image

AliciaC 3 years ago from British Columbia, Canada Author

Thank you for the lovely comment, Eddy! Dogs are wonderful animals. It's fascinating to learn about their abilities, and they can be loving and loyal companions.


AliciaC profile image

AliciaC 3 years ago from British Columbia, Canada Author

Thank you so much for the comment and the votes, Tom. I agree - dogs are amazing and fascinating! I hope that you have a very happy Christmas as well.


b. Malin profile image

b. Malin 3 years ago

What a Wonderful Hub Alicia. Dogs are Wonderful PEOPLE...I'm Serious! They are so attuned to us, and can sense so much. They give so much and expect just a pat, on the head in return. A lot of the information in your Hub is not new to me. But your presentation kept it so Interesting and enlightening, as well as Entertaining.

I'm a Dog lover and I bet you are too. Voted Up, Interesting, Useful, Awesome!

A Very Happy, Healthy Merry Christmas to YOU!


AliciaC profile image

AliciaC 3 years ago from British Columbia, Canada Author

Hi, b. Malin. Thank you so much for the lovely comment and all the votes!! Yes, I am definitely a dog lover! All the dog photos in this hub - except for the photo of the beagle - show dogs that are or have been a member of my family. I hope you have a very enjoyable Christmas!


Maren Morgan M-T profile image

Maren Morgan M-T 3 years ago from Pennsylvania

Thanks for an uplifting, warm-my-heart story. I needed it to balance the bad news pouring out of the media. :)


AliciaC profile image

AliciaC 3 years ago from British Columbia, Canada Author

Thank you for the visit, Maren Morgan. It is nice to hear good news when there is so much bad news being reported!


teaches12345 profile image

teaches12345 3 years ago

Wow, this is so fascinating! I love the fact that dogs can be used to help detect cancer, aid in detecting diabetes low-sugar and seizures. How wonderful!


AliciaC profile image

AliciaC 3 years ago from British Columbia, Canada Author

Hi, Dianna. Yes, it is wonderful that dogs can help detect medical problems! It's great that they have the ability and the willingness. Thanks for the comment.


aviannovice profile image

aviannovice 3 years ago from Stillwater, OK

This is amazing material. Dogs can do so much, including being helping dogs to those with arthritis and other physical limitations. They tracks during wars, and for police, too.


AliciaC profile image

AliciaC 3 years ago from British Columbia, Canada Author

Hi, Deb. It is amazing information about dogs! As you say, they can do so many other things to help us, too. Thanks for commenting.


PegCole17 profile image

PegCole17 3 years ago from Dallas, Texas

Fascinating material on an incredible subject. I loved the video of the dogs being trained to sniff out cancer. Amazing animals. Loved the pics too!


AliciaC profile image

AliciaC 3 years ago from British Columbia, Canada Author

Hi, Peg. I agree - dogs are amazing animals! Thank you very much for the comment.

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    Linda Crampton (AliciaC)1,248 Followers
    426 Articles

    Linda Crampton is a teacher with an honours degree in biology. She loves to study nature and write about animals and plants.



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